The subject invention is directed toward the art of monitoring devices and more particularly, to a device for monitoring the locking position of a connecting device including intermateable locking and support components. The invention is especially suited for monitoring the locked condition of a connecting device for fixing a child seat in a motor vehicle.
There are several established techniques for fixing a child seat in a motor vehicle. In one method, the child is placed into the child seat and then the seat together with the child are fastened to the motor vehicle using a two-point or three-point belt system already provided in the motor vehicle. In another method, the child seat can be first attached to the motor vehicle with additional belts installed in the vehicle. Thereafter the child is restrained using auxiliary belts integrated into the child seat itself.
The motor vehicle industry has recently developed new standards and a new connection system for child seats. These special child seats have integrated locking elements which are connected with rigid support elements provided in the motor vehicle. As an example, a pair of arms may be provided on the child seat which each respectively include frontal recess openings adapted to engage suitably formed U-shaped hoops which are firmly installed in the motor vehicle. After initially inserting the arms onto the hoop-shaped support components, the seat is thereafter more securely fastened by means of a locking device provided on the locking components or elsewhere on the child seat. This attachment system enables rapid installation of the child seat. Furthermore, since the child seat is solidly anchored to the motor vehicle, for all practical purposes there is no danger that the child seat will be torn from its anchorage during a collision.
One problem associated with child seats placed in motor vehicles, particularly when the child seats are placed on the front seat of the motor vehicle, is that air bag triggering must be prevented. Several systems have been developed for that purpose including infrared and ultrasound detection systems which attempt to ascertain whether or not a child seat is installed in the motor vehicle. Air bag triggering is prevented if the infrared or ultrasound detection systems determine that a seat is present. However, such systems can offer no guarantee of 100% accuracy.
In the art of restraining systems for motor vehicles in general, monitoring devices and methods are known for monitoring the locking position of a connecting device proper. As an example, monitors are available for determining the locked condition of a belt lock of a passenger restraining system. Such monitoring systems can be employed in order to prevent the triggering of an air bag in the event that there is no person in a particular seat, for example, the passenger seat. In those systems, when the belt associated with that seat is ascertained as being opened or unlocked, it is assumed that there is no person or passenger located on that associated seat. Traditional devices for monitoring the locking position of belt lock systems include, in most cases, a terminal switch which is contacted or otherwise actuated by a component of the belt lock system which is attached to the belt.
One problem with such systems, however, is that malfunctions are not always detectable. As an example, it is not possible to differentiate whether the belt lock is open or whether the circuit closer is defective and the electrical switch contact was not closed despite the successful locking of the belt lock components. In this context, unpublished German Patent Application 198 30 229 describes a device for monitoring the locking position of connecting devices which can be integrated in a simple fashion into existing and known belt lock connecting devices. The device for monitoring the locking position of the connecting devices described in the application accounts for this error condition.
The above monitoring device ascertains two (2) relative positions between the locking component and the support component of a connecting device during joining of the components from an unlocked to a locked condition. During joining of the components of the locking device, at least one displaceable tag on one of the components is moved from a first initial position to a second end position. First and second sensor devices respectively ascertain the presence or absence of the tag in the initial and end positions. Using this approach, it is possible to not only calibrate the monitored connecting device with regard to the locked condition of the components, but to ascertain connecting phases of the connecting process. As an example, it can be determined with this device if one of the pair of sensors has failed. In addition, the monitoring device can determine whether the tag has been destroyed.
The state of the art described above is limited, however. There remains a need for a device for monitoring the locking position of a connecting device, especially the locking position of a connecting device for fixing a child seat to a motor vehicle. It is preferred that the monitoring device can be installed in a simple fashion in a motor vehicle which is suitably provided with at least one support component of the overall child seat connecting device. It is also desirable to provide such a device which can monitor the connection state of a child seat connecting device in a simple fashion yet while anticipating the essential possibilities for failure.
The subject invention provides an apparatus for monitoring a locked condition of an associated connecting device adapted for attaching a child seat to a motor vehicle. The associated connecting device includes a support component attached to said motor vehicle and a locking component attached to said child seat. The apparatus comprises a base body selectively connectable with the support component, a slider on the base body and a detection device. The slider is movable relative to the base body during transfer of the locking component from an unlocked condition to a locking position. The slider is disposed on said base body at a location to contact the locking component and is adapted to be displaced from an initial slider position corresponding to the unlocked condition of the associated connecting device to an end slider position corresponding to the locking position of the associated connecting device. The detection device on the base body is adapted to detect said locked condition of the locking component and the support component by detecting the slider in said initial slider position when the associated locking component is in the unlocked condition, and detecting the slider in said end slider position when the associated locking component is in the locking position.
In accordance with an aspect of the invention, the subject device recognizes a common failure mode of prior art switch monitoring devices, namely that even though the connecting device is in a locked position and the end switch is activated, the internal contact may not be closed correctly due to wear and tear of the contact elements, or the like. Accordingly, in order to recognize this functional failure mode, the present invention monitors at least two positions of a slider member. More particularly, the device according to the present invention monitors not only the locked end position of the slider member but, in addition, monitors at least one other position of the slider a distance spaced apart from the locking position. As a result, the functional safety of the monitoring device is drastically improved.
As examples of improved safety, the device of the present invention recognizes a failure mode of the switches when the connecting device is in a locked condition by first monitoring the switch signals when the slider member is in a position spaced apart a distance from the locking position. This initial position of the slider member indicates an unlocked or pre-locked condition of the connecting device. Conversely, the present invention recognizes the opposite sensor failure mode, namely the mode in which the sensor detecting the unlocked condition of the connecting device is present. In that regard, a signal that the slider member is in a position indicating that the connecting device is in the locked condition but without first receiving a signal that the slider device represents the unlocked condition presents the opposite error condition.
In accordance with another aspect, the device of the present invention generates an xe2x80x9cunlockedxe2x80x9d failure signal only when there is an actual attempt of producing a locking connection between the locking and support components of the connecting device. The device of the present invention recognizes a locking attempt in two ways. In the first, the device monitors the movement of the slider member off from an initial position which indicates that the connecting device is in an unlocked condition. Also, a locking attempt is noted when the slider member transitions to a state indicating that the connecting device is moved to the locked condition. In contrast thereto, in prior art monitoring devices with simple end switches, it was only possible to generate a constant xe2x80x9cunlockedxe2x80x9d failure signal when the belts are not connected in the example of lap and shoulder belts, from starting the ignition of the vehicle until the actual locking of the connecting device. Systems of this type were used primarily in connection with restraining systems in automobiles whereby in actual practice, they turned out to be troublesome in that the failure signal was often generated, regardless of whether or not the operator wanted to actually produce a locking.
In accordance with a more detailed aspect of the invention, the monitoring device includes a basic body member which is formed so that it can be selectively locked together or screwed together with the support component of an associated connecting device. This results in an extremely simple installation of the monitoring device. Also, the present invention enables simple retrofitting capabilities. Each associated connecting device includes a locking component and a support component.
In accordance with a further aspect of the invention, the basic body includes a guidance region for the locking component. The guidance region defines an insertion channel for receiving the associated locking component portion of the associated connecting device. In that regard, this helps facilitate connection between the associated locking and support components when the connecting device is not readily visible or accessible without difficulty. This may occur, for example, when the support components are provided in the gap of a motor vehicle seat between the seating area and the back rest. In that case, the guidance region of the basic body of the subject device is suitably formed in a fashion so that it substantially extends into the gap between the seating area and the back rest so that the locking components of the connecting device, such as a child seat, can be simply inserted into the then visible openings of the guidance regions. The insertion channel defined by the guidance regions facilitates simple insertion of the locking components into the locking position.
In accordance with a further aspect of the invention, engagement recesses are provided in the side walls of the insertion channel. The engagement recesses are adapted to accept the support component of the connecting device. As a result, the base body of the monitoring device can be simply clipped onto the locking component prior to connection of the locking components onto the support components. This embodiment including the guidance region is also useful with known detection devices which monitor only the locking position. Further, the embodiment is useful in combination with additional previously and subsequently explained characteristics.
In accordance with a further aspect of the invention, the slider member is movable relative to the body member of the device. A region of the slider member is oriented in a vertical or transverse direction relative to the direction of movement of the slider relative to the body. That portion of the slider is adapted for contact with the locking element and extends laterally substantially the entire width of the support component and at least over the width of the insertion channel in the region of the support component. This ensures that the slider will be activated and not damaged during the connecting process when a relatively narrowly designed locking component is engaged with the associated support component into the locked position.
In accordance with another aspect of the invention, one or more magnets are provided on the slider member. A detection device, preferably a Hall effect element device generates a signal when one or both of the magnets are detected. It is to be appreciated that in accordance with the invention, the detection device detects both the initial position of the slider as well as the end position of the slider. By recording or ascertaining the initial position, it is possible to constantly monitor the functional capability of the overall monitoring device and/or of the sensor devices for monitoring the initial position of the slider.
In accordance with a further aspect of the invention, the detection device generates at least a first and a second non-zero electrical signal, whereby the first electrical signal corresponds to the initial position or a suitable initial position range of the slider (connecting device in an unlocked condition). The second electrical signal corresponds to the end position or a suitable end position range of the slider (connecting device in a locked condition). By comparing the signals with predetermined theoretical values or predetermined value ranges, the present invention ascertains both the functional capability of the overall device as well as the position of the slider and, thus, in particular, notes the correct locking position of the connecting device.
In addition to the above, the detection device is adapted for further analysis of the signals into several xe2x80x9coperating signalsxe2x80x9d or xe2x80x9cfailure signalsxe2x80x9d. As an example, an xe2x80x9coperating signalxe2x80x9d represents that the detected initial position of the slider is present and the locked position of the slider is not detected. Conversely, a xe2x80x9cnon-locking signalxe2x80x9d is generated as a failure signal when the detection device does not detect the initial position of the slider simultaneously with a non-detection of the locking position. This would indicate that the slider is between the first and second positions.
In accordance with another aspect of the invention, the detection device generates a third electrical signal when the slider is located between the initial position or range and the locking position or range. This is accomplished by ascertaining the non-detection of the tag on the slider represents that the slider is between the initial and the locking positions. Alternatively, a third sensor may be provided. Preferably, the third electrical signal is further processed into the xe2x80x9cfunctional signalsxe2x80x9d and/or xe2x80x9cfailure signalsxe2x80x9d by the detection device via inter-connection of the third with the other previously described signals.